Apparatus and method for transmitting and receiving phase compensation reference signal

ABSTRACT

A method and system for converging a 5th-generation (5G) communication system for supporting higher data rates beyond a 4th-generation (4G) system with a technology for Internet of Things (IoT) are provided. The present disclosure may be applied to intelligent services based on the 5G communication technology and the IoT-related technology, such as smart home, smart building, smart city, smart car, connected car, health care, digital education, smart retail, security and safety services. The method for transmitting and receiving a phase compensation reference signal (PCRS) to compensate for phase noise. The method may determine whether a first precoding is applied to a demodulation reference signal (DMRS) and the PCRS to be transmitted to a terminal. The base station may also generate the DMRS and the PCRS, based on whether the first precoding is applied to the DMRS and the PCRS, and transmit data, the DMRS, and the PCRS to the terminal.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit under 35 U.S.C. § 119(e) of a U.S.Provisional application filed on Aug. 5, 2016, in the U.S. Patent andTrademark Office and assigned Ser. No. 62/371,467, and under 35 U.S.C. §119(a) of a Korean patent application filed on Jul. 18, 2017, in theKorean Intellectual Property Office and assigned Serial number10-2017-0091042, the entire disclosures of each of which is herebyincorporated by reference.

TECHNICAL FIELD

The present disclosure relates to an apparatus and method fortransmitting and receiving a reference signal. More particularly, thepresent disclosure relates to an apparatus and method for transmittingand receiving a phase compensation reference signal.

BACKGROUND

Because demand for wireless data traffic has been increased sincedeployment of fourth generation (4G) communication systems, efforts havebeen made to develop an improved fifth generation (5G) or pre-5Gcommunication system. Therefore, the 5G or pre-5G communication systemis also called a ‘Beyond 4G Network’ or a ‘Post long term evolution(LTE) System’. The 5G communication system is considered to beimplemented in higher frequency (mmWave) bands, e.g., 60 GHz bands, soas to accomplish higher data rates. To decrease propagation loss of theradio waves and increase the transmission distance, the beamforming,massive multiple-input multiple-output (MIMO), full dimensional MIMO(FD-MIMO), array antenna, an analog beam forming, large scale antennatechniques are discussed in 5G communication systems. In addition, in 5Gcommunication systems, development for system network improvement isunder way based on advanced small cells, cloud radio access networks(RANs), ultra-dense networks, device-to-device (D2D) communication,wireless backhaul, moving network, cooperative communication,coordinated multi-points (CoMP), reception-end interference cancellationand the like. In the 5G system, hybrid frequency shift keying andquadrature amplitude modulation (FQAM) and sliding window superpositioncoding (SWSC) as an advanced coding modulation (ACM), and filter bankmulti carrier (FBMC), non-orthogonal multiple access(NOMA), and sparsecode multiple access (SCMA) as an advanced access technology have beendeveloped.

The Internet, which is a human centered connectivity network wherehumans generate and consume information, is now evolving to the Internetof Things (IoT) where distributed entities, such as devices, exchangeand process information without human intervention. The Internet ofEverything (IoE), which is a combination of the IoT technology and thebig data processing technology through connection with a cloud server,has emerged. As technology elements, such as “sensing technology”,“wired/wireless communication and network infrastructure”, “serviceinterface technology”, and “security technology” have been demanded forIoT implementation, a sensor network, a machine-to-machine (M2M)communication, machine Type communication (MTC), and so forth have beenrecently researched. Such an IoT environment may provide intelligentInternet technology services that create a new value to human life bycollecting and analyzing data generated among connected devices. IoT maybe applied to a variety of fields including a smart home, a smartbuilding, a smart city, a smart car or connected cars, a smart grid,health care, smart appliances and advanced medical services throughconvergence and combination between existing information technology (IT)and various industrial applications.

In line with this, various attempts have been made to apply 5Gcommunication systems to IoT networks. For example, technologies such asa sensor network, MTC, and M2M communication may be implemented bybeamforming, MIMO, and array antennas. Application of a cloud RAN as theabove-described big data processing technology may also be considered tobe as an example of convergence between the 5G technology and the IoTtechnology.

The 5G communication system is expected to use a high frequency band.

The above information is presented as background information only toassist with an understanding of the present disclosure. No determinationhas been made, and no assertion is made, as to whether any of the abovemight be applicable as prior art with regard to the present disclosure.

SUMMARY

Aspects of the present disclosure are to address at least theabove-mentioned problems and/or disadvantages and to provide at leastthe advantages described below. Accordingly, an aspect of the presentdisclosure is to provide a new reference signal to compensate for signalattenuation due to phase error. The disclosure also provide a method forefficiently transmitting a phase compensation reference signal forcompensating for a phase noise. More particularly, the presentdisclosure provides a method for a base station to generate and transmita phase compensation reference signal (PCRS) depending on whether thesame precoding as a demodulation reference signal (DMRS) is applied, andfor a terminal to estimate channel information by receiving the PCRS.

In accordance with an aspect of the present disclosure, a method of abase station in a communication system is provided. The method includesdetermining whether a first precoding is applied to a demodulationreference signal (DMRS) and a phase compensation reference signal (PCRS)to be transmitted to a terminal, generating the DMRS and the PCRS basedon whether the first precoding is applied to the DMRS and the PCRS, andtransmitting data, the DMRS, and the PCRS to the terminal

Additionally, the method of the base station may further comprisetransmitting, to the terminal, downlink control information includingantenna information indicating at least one antenna port associated withthe DMRS and at least one antenna port associated with the PCRS andprecoding information indicating whether the first precoding is applied.In the method, the precoding information indicates that the firstprecoding is applied to the at least one antenna port associated withthe DMRS and the at least one antenna port associated with the PCRS. TheDMRS may be used to estimate channel information, and the PCRS may beused to estimate a phase noise and to compensate the channelinformation.

In accordance with an aspect of the present disclosure, a method of aterminal in a communication system is provided. The method includesreceiving data, a DMRS, and a PCRS from a base station, determiningwhether a first precoding is applied to the DMRS and the PCRS, andestimating channel information using the DMRS and the PCRS based onwhether is the first precoding is applied to the DMRS and the PCRS.

In accordance with an aspect of the present disclosure, a base stationin a communication system comprises a transceiver configured to transmitand receive a signal, and a controller configured to determine whether afirst precoding is applied to a DMRS and a PCRS to be transmitted to aterminal, generate the DMRS and the PCRS based on whether the firstprecoding is applied to the DMRS and the PCRS, and transmit data, theDMRS, and the PCRS to the terminal.

In accordance with an aspect of the present disclosure, a terminal in acommunication system comprises a transceiver configured to transmit andreceive a signal, and a controller configured to receive data, a DMRS,and a PCRS from a base station, determine whether a first precoding isapplied to the DMRS and the PCRS, and estimate channel information byusing the DMRS and the PCRS based on whether is the first precoding isapplied to the DMRS and the PCRS.

In accordance with an aspect of the present disclosure, since the basestation transmits the PCRS and the terminal receives the PCRS andestimates channel information with a compensated phase noise, a moreefficient signal transmission and reception are performed.

Other aspects, advantages, and salient features of the disclosure willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses various embodiments of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainembodiments of the present disclosure will be more apparent from thefollowing description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a diagram illustrating an example in which a demodulationreference signal (DMRS) and a phase compensation reference signal (PCRS)are mapped based on frequency-time resources according to an embodimentof the present disclosure;

FIG. 2 is a diagram illustrating an example in which a DMRS is mappedbased on frequency-time resources according to an embodiment of thepresent disclosure;

FIG. 3 is a diagram illustrating an example in which a PCRS is mappedbased on frequency-time resources according to an embodiment of thepresent disclosure;

FIGS. 4A and 4B are diagrams illustrating operations of a base stationand a terminal when the base station performs a signal transmission tothe terminal by using a single antenna port according to variousembodiments of the present disclosure;

FIGS. 5A and 5B are diagrams illustrating operations of a base stationand a terminal when the base station performs a signal transmission tothe terminal by using a transmit diversity according to variousembodiments of the present disclosure;

FIGS. 6A and 6B are diagrams illustrating operations of a base stationand a terminal when the base station performs a signal transmission tothe terminal by using a transmit diversity according to variousembodiments of the present disclosure;

FIGS. 7A and 7B are diagrams illustrating operations of a base stationand a terminal when the base station performs a signal transmission tothe terminal by using a spatial multiplexing with a single layeraccording to various embodiments of the present disclosure;

FIGS. 8A and 8B are diagrams illustrating operations of a base stationand a terminal when the base station performs a signal transmission tothe terminal by using a spatial multiplexing with a single layeraccording to various embodiments of the present disclosure;

FIGS. 9A and 9B are diagrams illustrating operations of a base stationand a terminal when the base station performs a signal transmission tothe terminal by using a spatial multiplexing with two layers accordingto various embodiments of the present disclosure;

FIGS. 10A and 10B are diagrams illustrating operations of a base stationand a terminal when the base station performs a signal transmission tothe terminal by using a spatial multiplexing with two layers accordingto various embodiments of the present disclosure;

FIGS. 11A and 11B are diagrams illustrating operations of a base stationand a terminal when the base station performs a signal transmission tothe terminal by using a spatial multiplexing with two layers accordingto various embodiments of the present disclosure;

FIGS. 12A and 12B are diagrams illustrating operations of a base stationand a terminal when the base station performs a signal transmission tothe terminal by using a spatial multiplexing with two layers accordingto various embodiments of the present disclosure;

FIG. 13 is a diagram illustrating a structure and operation of a channelestimation block of a terminal when the same precoder is used for a DMRSand a PCRS according to various embodiments of the present disclosure;

FIGS. 14A and 14B are diagrams illustrating a structure and operation ofa channel estimation block of a terminal when the same precoder is notused for a DMRS and a PCRS according to various embodiments of thepresent disclosure;

FIG. 15 is a diagram illustrating a structure of a terminal according toan embodiment of the present disclosure; and

FIG. 16 is a diagram illustrating a structure of a base stationaccording to an embodiment of the present disclosure.

Throughout the drawings, it should be noted that like reference numbersare used to depict the same or similar elements, features, andstructures.

DETAILED DESCRIPTION

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of variousembodiments of the present disclosure as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the various embodiments describedherein can be made without departing from the scope and spirit of thepresent disclosure. In addition, descriptions of well-known functionsand constructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are notlimited to the bibliographical meanings, but, are merely used by theinventor to enable a clear and consistent understanding of the presentdisclosure. Accordingly, it should be apparent to those skilled in theart that the following description of various embodiments of the presentdisclosure is provided for illustration purpose only and not for thepurpose of limiting the present disclosure as defined by the appendedclaims and their equivalents.

It is to be understood that the singular forms “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, reference to “a component surface” includes referenceto one or more of such surfaces.

For the same reason, some elements are exaggerated, omitted orschematically shown in the accompanying drawings. Also, the size of eachelement does not entirely reflect the actual size. In the drawings, thesame or corresponding elements are denoted by the same referencenumerals.

The advantages and features of the present disclosure and the manner ofachieving them will become apparent with reference to the embodimentsdescribed in detail below with reference to the accompanying drawings.The present disclosure may, however, be embodied in many different formsand should not be construed as limited to the embodiments set forthherein. Rather, these embodiments are provided so that this disclosurewill be thorough and complete, and will fully convey the scope of thedisclosure to those skilled in the art. To fully disclose the scope ofthe disclosure to those skilled in the art, and the disclosure is onlydefined by the scope of the claims.

It will be understood that each block of the flowchart illustrations,and combinations of blocks in the flowchart illustrations, may beimplemented by computer program instructions. These computer programinstructions may be provided to a processor of a general purposecomputer, special purpose computer, or other programmable dataprocessing apparatus to produce a machine, such that the instructions,which are executed via the processor of the computer or otherprogrammable data processing apparatus, generate means for implementingthe functions specified in the flowchart block or blocks. These computerprogram instructions may also be stored in a computer usable orcomputer-readable memory that may direct a computer or otherprogrammable data processing apparatus to function in a particularmanner, such that the instructions stored in the computer usable orcomputer-readable memory produce an article of manufacture includinginstruction means that implement the function specified in the flowchartblock or blocks. The computer program instructions may also be loadedonto a computer or other programmable data processing apparatus to causea series of operations to be performed on the computer or otherprogrammable apparatus to produce a computer implemented process forimplementing the functions specified in the flowchart block or blocks.

And each block of the flowchart illustrations may represent a module,segment, or portion of code, which comprises one or more executableinstructions for implementing the specified logical function(s). Itshould also be noted that in some alternative implementations, thefunctions noted in the blocks may occur out of the order. For example,two blocks shown in succession may in fact be executed substantiallyconcurrently or the blocks may sometimes be executed in the reverseorder, depending upon the functionality involved.

The term “unit”, as used herein, may refer to a software or hardwarecomponent or device, such as a field programmable gate array (FPGA) orapplication specific integrated circuit (ASIC), which performs certaintasks. A unit may be configured to reside on an addressable storagemedium and configured to execute on one or more processors. Thus, amodule or unit may include, by way of example, components, such assoftware components, object-oriented software components, classcomponents and task components, processes, functions, attributes,procedures, subroutines, segments of program code, drivers, firmware,microcode, circuitry, data, databases, data structures, tables, arrays,and variables. The functionality provided for in the components andmodules/units may be combined into fewer components and modules/units orfurther separated into additional components and modules.

Wireless communication systems provide high-speed, high-quality packetdata services, based on communication standards such as the 3rdgeneration partnership project (3 GPP) long term evolution (LTE) orevolved universal terrestrial radio access (E-UTRA), LTE-advanced(LTE-A), IEEE 802.16e, and the like. In addition, standards for the 5thgeneration (5G) wireless communication system or new radio (NR)communication standards are now studied. The present disclosure may beapplied to the 5G system and any other similar communication system bythose of skilled in the art.

For signal transmission, the LTE and LTE-A systems employ the orthogonalfrequency division multiplexing (OFDM) scheme for downlink (DL) and thesingle carrier frequency division multiple access (SC-FDMA) scheme foruplink (UL). In this OFDM-based wireless communication system accordingto the related art, a common phase error (CPE) which commonly affectsall OFDM subcarriers may be estimated and compensated for by using areference signal in the frequency domain.

To ensure an efficient frequency band, the next generation communicationsystems are expected to use high frequency bands such as millimeterwaves (mmWave). In such a high frequency band, signal attenuation due tothe influence of a phase error largely occurs. The phase error is causedby the incompleteness of an oscillator. Particularly, in communicationenvironments that use higher order modulation schemes (e.g., 16 QAM, 64QAM, 256 QAM), the signal restoration capability is affected byinter-carrier interference (ICI) that occurs because of the phase error.To estimate this phase error, a phase compensation reference signal(PCRS) may be introduced in the 5G system.

A demodulation reference signal (DMRS) used in the 5G system may betransmitted through a specific OFDM symbol in a subframe. In thecorresponding OFDM symbols, a plurality of DMRS antenna ports may besimultaneously transmitted without interference between them by usingfrequency division multiplexing (FDM) scheme, a code divisionmultiplexing (CDM) scheme, or a FDM and CDM scheme.

FIG. 1 is a diagram illustrating an example in which a DMRS and a PCRSare mapped based on frequency-time resources according to an embodimentof the present disclosure.

Referring to FIG. 1, the DMRS 120 may be transmitted in resources on thetime axis 100 and the frequency axis 110, and may be transmitted only inthe third symbol along the frequency axis.

The PCRS 130 may be transmitted through the remaining OFDM symbolsexcept some OFDM symbols along the time axis in the subframe. In thecorresponding OFDM symbols, a plurality of PCRS antenna ports may besimultaneously transmitted without interference between them by usingthe FDM scheme, the CDM scheme, or the FDM and CDM scheme. For example,as shown in FIG. 1, the PCRS 130 may be transmitted in the remainingOFDM symbols except the third OFDM symbol for transmitting the DMRS andthe first OFDM symbol for transmitting DL control information. Forexample, a base station may allocate up to two PCRS antenna ports usingtwo resource elements (REs) per four resource blocks (RBs) (including 48REs on the frequency axis), based on the FDM, and then transmit them toa terminal.

The base station may allocate DMRS antenna ports (hereinafter, may beshortly referred to as ports) p₁, . . . , p_(M) to the terminal by usingdownlink control information (DCI). For example, p₁ may have one ofvalues in a set {8, 9, . . . , 15}.

FIG. 2 is a diagram illustrating an example in which a DMRS is mappedbased on frequency-time resources according to an embodiment of thepresent disclosure.

Referring to FIG. 2, the DMRS may be transmitted via FDM and CDM todifferent REs for each port. Namely, the FDM may be applied to portnumbers {8, 9, 10, 11} for transmission on different REs according toport numbers. Also, the FDM may be applied to port numbers {12, 13, 14,15} for transmission on different REs according to port numbers.Meanwhile, the RE resource of the same location is used for port numbers{8, 12} and for transmission based on the CDM. Also, the RE resource ofthe same location is used for port numbers {9, 13} and for transmissionbased on the CDM. Also, the RE resource of the same location is used forport numbers {10, 14} and for transmission based on the CDM. Also, theRE resource of the same location is used for port numbers {11, 15 } andfor transmission based on the CDM.

The above-described DMRS may be generated, mapped to the RE, andtransmitted according to a detailed method described below in Table 1.However, embodiments of the present disclosure are not limited to aspecific method as shown in Table 1. Namely, embodiments of the presentdisclosure may be also applied to the DMRS generated by any othermethod.

The base station may allocate PCRS ports q₁, . . . , q_(K) to theterminal by using the DCI. For example, q_(i) may have one of values ina set {60, 61}. Alternatively, the PCRS port q_(i) may have the samevalue as the DMRS port p₁ has. For example, q₁ may have one of values ina set {8, 9, . . . , 15}. Allocation information for the PCRS port maybe explicitly included in the DCI, and in this case the DCI may includevalues of the PCRS ports q₁, . . . , q_(K). Meanwhile, allocationinformation for the PCRS port may be implicitly included in the DCI, andin this case the DCI may not explicitly include the PCRS ports q₁, . . ., q_(K). In this case, the terminal may presume the PCRS port allocationinformation according to methods proposed by embodiments of the presentdisclosure and perform related operations.

FIG. 3 is a diagram illustrating an example in which a PCRS is mappedbased on frequency-time resources according to an embodiment of thepresent disclosure.

Referring to FIG. 3, the PCRS may be mapped to different REs for to port300 and port 310 and having values in a set {60, 61}, namely, being FDM,and then transmitted.

The PCRS may be generated, mapped to the RE, and transmitted accordingto a detailed method described below in Table 2 with respect to PCRSports 300 and 310 having values in a set {60, 61}. However, embodimentsof the present disclosure are not limited to a specific method as shownin Table 2. Namely, embodiments of the present disclosure may be alsoapplied to the PCRS generated by any other method.

TABLE 2 6.7.6 DL Phase noise compensation reference signal Phase noisecompensation reference signals associated with xPDSCH are transmitted onantenna port(s) p = 60 and/or p = 61 as signaled in DCI format in [2];are present and are a valid reference for phase noise compensation onlyif the xPDSCH transmission is associated with the corresponding antennaport according to[3]; are transmitted only on the physical resourceblocks and symbols upon which the corresponding xPDSCH is mapped; areidentical in all symbols corresponding to xPDSCH allocation. 6.7.6.1Sequence generation For any of the antenna ports p ∈ {60, 61}, thereference-signal sequence _(r(m)) is defined by $\quad\begin{matrix}{{{r(m)} = {{\frac{1}{\sqrt{2}}\left( {1 - {2 \cdot {c\left( {2m} \right)}}} \right)} + {j\frac{1}{\sqrt{2}}\left( {1 - {2 \cdot {c\left( {{2m} + 1} \right)}}} \right)}}},} \\{{m = 0},1,\ldots \mspace{14mu},{\left\lfloor {N_{RB}^{\max,{DL}}/4} \right\rfloor - 1.}}\end{matrix}$ The pseudo-random sequence _(c(i)) is defined in clause7.2. The pseudo-random sequence generator shall be initialised withc_(init) = (└n_(s) / 2 ┘ + 1) · (2n_(ID) ^((n) ^(SCID) ⁾ + 1) · 2¹⁶ +n_(SCID) at the start of each subframe. The quantities n_(ID) ^((i)), i= 0, 1, are given by n_(ID) ^((i)) = N_(ID) ^((cell)) if no value forn_(ID) ^(PCRS,i) is proveded by higher layers n_(ID) ^((i)) = n_(ID)^(PCRS,i) otherwise The value of n_(SCID) is zero unless specifiedotherwise. For a xPDSCH transmission, n_(SCID) is given by the DCIformat in [2] associated with the xPDSCH transmission. 6.7.6.2 Mappingto resource elements For antenna ports _(p ∈ {60, 61}), in a physicalresource block with frequency-domain index _(n) _(PR B) ′ assigned forthe corresponding xPDSCH transmission, a part of the reference signalsequence _(r (m)) shall be mapped to complex-valued modulation symbolsa_(k,l) ^((p)) for all xPDSCH symbols in a subframe according to:a_(k,l′) ^((p)) = r(k″), where p′ is the demodulation reference signalport number associated with xPDSCH transmission. The starting resourceblock number of xPDSCH physical resource allocation n_(PRB) ^(xPDSCH) inthe frequency domain, resource allocation bandwidth in terms of numberof resource blocks N_(PRB) ^(xPDSCH) and resource elements (k, l′) in asubframe is given by $\quad\begin{matrix}{k = {{N_{sc}^{RB} \cdot \left( {n_{PRB}^{x{PDSCH}} + {k^{''} \cdot 4}} \right)} + k^{\prime}}} \\{k^{\prime} = \left\{ {\begin{matrix}24 \\23\end{matrix}\begin{matrix}{p \in 60} \\{p \in 61}\end{matrix}} \right.} \\{k^{''} = \left\lfloor {m^{\prime}/4} \right\rfloor} \\{{l^{\prime} = {l^{\prime}}_{first}^{xPDSCH}},\ldots \mspace{14mu},{l^{\prime}}_{last}^{xPDSCH}} \\{{m^{\prime} = 0},1,2,\ldots \mspace{14mu},{N_{PRB}^{x{PDSCH}} - 1}}\end{matrix}$ where l′ is the symbol index within a subframe. l′_(first)^(xPDSCH) and l′_(last) ^(xPDSCH) are symbol indices of the first andlast of xPDSCH, respectively for the given subframe. Resource elements(k, l′) used for transmission of UE- specific phase noise compensationreference signals on any of the antenna ports in the set S, where S ={60 } and S = {61 } shall not be used for transmission of xPDSCH on anyantenna port in the same subframe.

Hereinafter, an embodiment of the present disclosure will be describedwith respect to an associated relation for phase tracking between a DMRSantenna port group (or a port group) and a PCRS antenna port.Specifically, a method for associating a single PCRS port to be used forphase tracking with a DMRS antenna port group formed of one or more DMRSports is described.

An associated relation between a DMRS port p_(i) and a PCRS port whichare allocated to the terminal by the base station using one DCI, may bedefined as follows.

If the base station allocates one DMRS port p₁ and one PCRS port q₁ tothe terminal, the terminal may presume that there is the associatedrelation between the allocated DMRS port p₁ and the allocated PCRS portq₁.

If the base station allocates two or more DMRS ports p₁, . . . , p_(N)and one PCRS port q₁ to the terminal, the terminal may presume thatthere is the associated relation between all the DMRS ports p₁, . . . ,p_(N) and one PCRS port q₁ (Namely, this means a mapping relation ofN:1.). In this case, the DMRS ports p₁, . . . , p_(N) may be referred toas one DMRS port group, and all the DMRS ports included in the one DMRSport group have the associated relation with the PCRS port q₁.

If the base station allocates the same number of DMRS ports p₁, . . . ,p_(N) and PCRS ports q₁, . . . , q_(N) to the terminal, the terminal maypresume that there is the associated relation between antenna portshaving the same index value (j=i) in each DMRS port p_(j) and each PCRSport q_(i).

If the base station allocates a different number of DMRS ports p₁, . . ., p_(N) and PCRS ports q₁, . . . , q_(M) to the terminal, the basestation may further deliver information, j=Func_(mapping)(i), about amapping relation between N DMRS ports p_(j) and M PCRS ports q_(i) tothe terminal through the downlink control information (DCI). Based onthis information about the mapping relation, the terminal may presumethat there is the associated relation between the DMRS port p_(j) andthe PCRS port q_(i). Information about one or more mapping relations maybe set in advance in the terminal by using radio resource control (RRC)signaling or a media access control (MAC) control element (CE). The basestation may instruct the terminal on which mapping relation will beapplied, using the DCI.

If the base station allocates the DMRS and PCRS ports to the terminal byusing two or more DCI, the associated relation between the DMRS portp_(i) and the PCRS port q_(i) may be defined as follows. In embodimentsof the present disclosure, it is presumed that the base station uses KDCI. In the following description, one of the K DCI (i.e., DCI₁, DCI₂,DCI_(k)) will be referred to as DCI_(k).

If the base station allocates one DMRS port p_(1,k) and one PCRS portq_(1,k) to the terminal by using DCI_(k), the terminal may presume thatthere is the associated relation between the allocated DMRS port p_(1,k)and the allocated PCRS port q_(1,k).

If the base station allocates two or more DMRS ports p_(1,k), . . . ,p_(N,k) and one PCRS port q_(1,k) to the terminal by using DCI_(k), theterminal may presume that there is the associated relation between allthe DMRS ports p_(1,k), . . . , p_(N,k) and one PCRS port q_(1,k)(Namely, this means a mapping relation of N:1.). In this case, the DMRSports p_(1,k), . . . , p_(N,k) may be referred to as one DMRS portgroup, and all the DMRS ports included in the one DMRS port group havethe associated relation with the PCRS port q_(1,k).

If the base station allocates the same number of DMRS ports p_(1,k), . .. , p_(N,k) and PCRS ports q_(1,k), . . . , q_(N,k) to the terminal byusing DCI_(k), the terminal may presume that there is the associatedrelation between antenna ports having the same index value (j=i) in eachDMRS port p_(j,k) and each PCRS port q_(i,k).

If the base station allocates a different number of DMRS ports p_(i,k),. . . , p_(N,k) and PCRS ports q_(1,k), . . . , q_(M,k) to the terminalby using DCI_(k), the base station may further deliver information,j=Func_(mapping)(i), about a mapping relation between N DMRS portsp_(j,k) and M PCRS ports q_(i,k) to the terminal through the DCI. Basedon this information about the mapping relation, the terminal may presumethat there is the associated relation between the DMRS port p_(j,k) andthe PCRS port q_(i,k). Information about one or more mapping relationsmay be set in advance in the terminal by using RRC signaling or a MACCE. The base station may instruct the terminal on which mapping relationwill be applied, using the DCI.

In addition to the above-discussed method using a plurality of DCI, aplurality of DMRS and PCRS allocation information fields included in oneDCI may be used. Namely, in order to deliver the DMRS and PCRSallocation information, one DCI may include an information field 1, aninformation field 2, . . . , and an information field K. In this case, aphrase “DCI_(k)” used in the above description may be replaced by “thek-th information field for DMRS and PCRS allocation”.

If the base station allocates the DMRS and PCRS ports to the terminal byusing K information fields included in one DCI, the associated relationbetween the DMRS port p₁ and the PCRS port q_(i) which are allocated inone information field may be defined as follows.

If the base station allocates one DMRS port p_(1,k) and one PCRS portq_(1,k) to the terminal by using the k-th information field, theterminal may presume that there is the associated relation between theallocated DMRS port p_(1,k) and the allocated PCRS port q_(1,k).

If the base station allocates two or more DMRS ports p_(1,k), . . . ,p_(N,k) and one PCRS port q_(1,k) to the terminal by using the k-thinformation field, the terminal may presume that there is the associatedrelation between all the DMRS ports p_(1,k), . . . , p_(N,k) and onePCRS port q_(1,k) (Namely, this means a mapping relation of N:1.). Inthis case, the DMRS ports p_(1,k), . . . , p_(N,k) may be referred to asone DMRS port group, and all the DMRS ports included in the one DMRSport group have the associated relation with the PCRS port q_(1,k).

If the base station allocates the same number of DMRS ports p_(1,k), . .. , p_(N,k) and PCRS ports q_(1,k), . . . , q_(N,k) to the terminal byusing the k-th information field, the terminal may presume that there isthe associated relation between antenna ports having the same indexvalue (j=i) in each DMRS port p_(j,k) and each PCRS port q_(i,k).

If the base station allocates a different number of DMRS ports p_(1,k),. . . , p_(N,k) and PCRS ports q_(1,k), q_(M,k) to the terminal by usingthe k-th information field, the base station may further deliverinformation, j=Func_(mapping)(i), about a mapping relation between NDMRS ports p_(j,k) and M PCRS ports q_(i,k) to the terminal through theDCI. Based on this information about the mapping relation, the terminalmay presume that there is the associated relation between the DMRS portp_(j,k) and the PCRS port q_(i,k).

According to embodiments of the present disclosure, information aboutthe associated relation between the DMRS port and the PCRS part may beset in the terminal by the base station through RRC signaling or a MACCE message. One associated relation includes information about a pair of(j, i) having a relation of j=Func_(mapping)(i), and this informationabout a pair is defined as N pieces for different j values. The terminalmay presume that the DMRS port p_(j) and the PCRS port q_(i)corresponding to the one pair (j, i) have the associated relation witheach other.

Table 3 below shows three different associated relations in case of N=4and M=2. As shown in Table 3, one or more associated relations may beset in the terminal through the RRC signaling or the MAC CE message withrespect to specific N and M values, and each of the set associatedrelations may have a unique index. The base station may instruct theterminal on the index of one of the set associated relations through theDCI. The terminal may apply the associated relation corresponding to theinstructed index to the associated relation between DMRS and PCRS portsallocated through the DCI.

TABLE 3 Index for associated Mapping rule (j, i) respectively forrelation DMRS port p_(j) and PCRS port q_(i) #1 (j, i) = (1, 1), (2, 1),(3, 1), (4, 2) #2 (j, i) = (1, 1), (2, 1), (3, 2), (4, 2) #3 (j, i) =(1, 1), (2, 2), (3, 2), (4, 2)

According to another embodiment of the present disclosure, an explicitassociated relation between the DMRS port number p and the PCRS portnumber q may be set in advance in the terminal by the base stationthrough the RRC signaling or the MAC CE. For example, when DMRS ports 8,9, 10, . . . , 16 and PCRS ports 60, 61 are defined in the standard, thebase station may set a specific DMRS port number p that has anassociated relation with a specific PCRS port number q.

Table 4 below shows associated relations between the DMRS port and thePCRS port which are settable by the base station. Specifically,according to the first associated relation defined in Table 4, the PCRSport 60 has the associated relation with the DMRS ports 8, 9, 10 and 11,and the PCRS port 61 has the associated relation with the DMRS ports 12,13, 14 and 15. According to the second associated relation defined inTable 4, the PCRS port 60 has the associated relation with the DMRSports 8, 10, 12 and 14, and the PCRS port 61 has the associated relationwith the DMRS ports 9, 11, 13 and 15. According to the third associatedrelation in Table 4, the PCRS port 60 has the associated relation withall the DMRS ports. According to the fourth associated relation in Table4, the PCRS port 61 has the associated relation with all the DMRS ports.

If one or more associated relations may be set through the RRC signalingor the MAC CE, each of the set associated relations may have a uniqueindex. The base station may instruct the terminal on the index of one ofthe set associated relations through the DCI. The terminal may apply theassociated relation corresponding to the instructed index to theassociated relation between DMRS and PCRS ports allocated through theDCI.

TABLE 4 Index for associated relation PCRS port DMRS port #1 60 8, 9,10, 11 61 12, 13, 14, 15 #2 60 8, 10, 12, 14 61 9, 11, 13, 15 #3 60 8,9, 10, 11, 12, 13, 14, 15 #4 61 8, 9, 10, 11, 12, 13, 14, 15

In addition, the base station may correlate the DMRS ports, which areexpected to cause phase noises of the same value, with one PCRS port.

If it is expected that phase noises of the same value will occur on allthe DMRS ports allocated to the terminal, the base station may set allDMRS ports p₁, . . . , p_(N) allocated by the above-discussed method tohave the associated relation with one PCRS port q₁.

If it is expected that phase noises of different values will occur onthe respective DMRS ports allocated to the terminal, the base stationmay set the antenna ports having the same index value (j=i) to have theassociated relation with each other among the DMRS ports p_(j) and thePCRS ports q_(i) allocated by the above-discussed method.

If it is expected that phase noises of the same value will occur on someof the DMRS ports allocated to the terminal and further phase noises ofdifferent values will occur on the others, the base station may allocateone PCRS port to only some of the DMRS ports on which phase noises ofthe same value are expected to occur.

In addition to the above-described phase noise, the base station maycorrelate the DMRS ports, which are expected to cause time-axis channelvariations of the same value for each symbol, with one PCRS port.Therefore, although only the phase noise estimation is exemplarily usedfor the following description, the present disclosure is not limited tothe phase noise estimation and may be also applied to all kinds oftime-axis channel variations.

Regarding the PCRS port q_(i) and the DMRS port p_(j) which have anassociated relation with each other, the terminal may use informationestimated based on the PCRS port q_(i) to compensate informationestimated on the associated DMRS port p_(j). The information estimatedusing the PCRS port q_(i) may be phase noise information for OFDMsymbols in the subframe, channel variation information that istime-varying between adjacent OFDM symbols in the subframe, or channelinformation estimated in a specific OFDM symbol in the subframe. Theestimated channel information refers to channel information to whicharbitrary precoding is applied according to the multiple-input andmultiple-output (MIMO) transmission scheme used by the base station.

The compensation of the information estimated on the DMRS port mayinclude compensation for channel information that varies by a phasenoise for each OFDM symbol, compensation for channel information thatvaries with time between OFDM symbols, or compensation for both thechannel information varying by a phase noise for each OFDM symbol andthe channel information time-varying between OFDM symbols.

Hereinafter, various embodiments of the present disclosure will bedescribed with respect to a channel estimation method of the terminalusing one DMRS port and one PCRS port which are associated with eachother.

If the same precoding is applied to the DMRS port p_(j) and the PCRSport q_(i) which are associated with each other, the terminal mayperform the following channel estimation method using this. In thiscase, {tilde over (h)}_(k,2) ^(p) ^(j) denotes channel information ofthe DMRS port p_(j) with respect to the second OFDM symbol and the k-thRE, and may be estimated by the terminal using the DMRS port p_(j)located in the second OFDM symbol. {tilde over (h)}_(k,l) ^(q) ^(i)denotes channel information of the PCRS port q_(i) with respect to thel-th OFDM symbol and the k-th RE, and may be estimated by the terminalusing the PCRS port q_(i) located in the l-th OFDM symbol.

If the same precoding is applied to the DMRS port p_(j) and the PCRSport q_(i), the terminal may estimate a channel value for the DMRS portp_(j) with respect to the l-th OFDM symbol and the k-th RE, as shown inEquation 1.

ĥ _(k,l) ^(p) ^(j) =|{tilde over (h)} _(k,2) ^(p) ^(j) |exp(j∠({tildeover (h)} _(k,l) ^(q) ^(i) ))   Equation 1

If the same precoding is applied to the DMRS port p_(j) and the PCRSport q_(i), the terminal may also estimate a channel value for the DMRSport p_(j) with respect to the l-th OFDM symbol and the k-th RE, asshown in Equation 2.

ĥ _(k,l) ^(p) ^(j) ={tilde over (h)} _(k,2) ^(p) ^(j) exp(jΔ{circumflexover (θ)} _(k,l))   Equation 2

Herein, a phase difference value for the k-th RE between the second OFDMsymbol and the l-th OFDM symbol may be estimated as shown in Equation 3.In order to increase the estimation accuracy, the terminal may use avalue obtained by taking a cumulative average of a plurality of REindexes k. In this case, a phase difference may be caused by theabove-described phase noise, or may be caused by a time-varying channelin a situation where the terminal moves.

Δ{circumflex over (θ)}_(k,l)=∠({tilde over (h)} _(k,l) ^(q) ^(i) ({tildeover (h)} _(k,2) ^(p) ^(i) )*)   Equation 3

If different precodings are applied to the DMRS port p₁ and the PCRSport q_(i) which are associated with each other, the terminal mayperform the following channel estimation method using this. In thiscase, {tilde over (h)}_(k,2) ^(p) ^(j) denotes channel information ofthe DMRS port p_(j) with respect to the second OFDM symbol and the k-thRE, and may be estimated by the terminal using the DMRS port p_(j)located in the second OFDM symbol. {tilde over (h)}_(k,l) ^(q) ^(i)denotes channel information of the PCRS port q_(i) with respect to thel-th OFDM symbol and the k-th RE, and may be estimated by the terminalusing the PCRS port q_(i) located in the l-th OFDM symbol.

A phase difference value for the k-th RE in the l-th OFDM symbol may beestimated as shown in Equation 4.

In order to increase the estimation accuracy, the terminal may use avalue obtained by taking a cumulative average of a plurality of REindexes k. In this case, a phase difference may be caused by theabove-described phase noise, or may be caused by a time-varying channelin a situation where the terminal moves. Also, depending on a receptionalgorithm of the terminal, a value of a channel magnitude difference aswell as a phase difference may be estimated.

Δ{circumflex over (θ)}_(k,l)=∠({tilde over (h)} _(k,l+1) ^(q) ^(i)({tilde over (h)} _(k,l) ^(q) _(i))*)   Equation 4

In case of the DMRS port p_(j) to which precoding different from that ofthe PCRS port q_(i) is applied, the channel value for the DMRS portp_(j) with respect to the l-th OFDM symbol and the k-th RE may beestimated as shown in Equation 5.

ĥ _(k,3) ^(p) ^(j) ={tilde over (h)} _(k,2) ^(p) ^(j)exp(j∠(Δ{circumflex over (θ)}_(k,3)))

ĥ _(k,4) ^(p) ^(j) ={tilde over (h)} _(k,2) ^(p) ² exp(j∠(Δ{circumflexover (θ)}_(k,3)+Δ{circumflex over (θ)}_(k,4)))

ĥ _(k,l) ^(p) ^(j) ={tilde over (h)} _(k,2) ^(p) ² exp(j∠(Δ{circumflexover (θ)}_(k,3)+Δ{circumflex over (θ)}_(k,4)+ . . . +Δ{circumflex over(θ)}_(k,l)))   Equation 5

If the same precoding is applied to the DMRS port p₁ and the PCRS portq₁ with respect to the DMRS ports p₁, p₂ and the PCRS port q₁ which areassociated with each other, the terminal may perform the followingchannel estimation method using this. In this case, {tilde over(h)}_(k,2) ^(p) ^(j) denotes channel information of the DMRS port p_(j)with respect to the second OFDM symbol and the k-th RE, and may beestimated by the terminal using the DMRS port p_(j) located in thesecond OFDM symbol. {tilde over (h)}_(k,l) ^(q) ¹ denotes channelinformation of the PCRS port q₁ with respect to the l-th OFDM symbol andthe k-th RE, and may be estimated by the terminal using the PCRS port q₁located in the l-th OFDM symbol.

If the same precoding is applied to the DMRS port p₁ and the PCRS portq₁, a channel value for the DMRS port p₁ with respect to the l-th OFDMsymbol and the k-th RE may be estimated as shown in Equation 6.

ĥ _(k,l) ^(p) ¹ =|{tilde over (h)} _(k,2) ^(p) ¹ |exp(j∠({tilde over(h)} _(k,l) ^(q) ¹ ))   Equation 6

In case of the DMRS port p₁ to which the same precoding as that of thePCRS port q₁ is applied, the channel value for the DMRS port p₁ withrespect to the l-th OFDM symbol and the k-th RE may be estimated asshown in Equation 7.

ĥ _(k,l) ^(p) ¹ ={tilde over (h)} _(k,2) ^(p) ¹ exp(jΔ{circumflex over(θ)}_(k,l))   Equation 7

A phase difference value for the k-th RE in the l-th OFDM symbol may beestimated as shown in Equation 8. In order to increase the estimationaccuracy, the terminal may use a value obtained by taking a cumulativeaverage of a plurality of RE indexes k. In this case, a phase differencemay be caused by the above-described phase noise, or may be caused by atime-varying channel in a situation where the terminal moves. Also,depending on a reception algorithm of the terminal, a value of a channelmagnitude difference as well as a phase difference may be estimated.

Δ{circumflex over (θ)}_(k,l)=∠({tilde over (h)} _(k,l) ^(q) ¹ ({tildeover (h)} _(i,2) ^(p) ¹ )*)   Equation 8

Since the PCRS port q₁ and the DMRS ports (p₁, p₂) are associated witheach other for the phase estimation, the terminal may use the phasevariation value, estimated using the DMRS port p₁ and the PCRS port q₁,for a phase correction of a channel estimated with respect to the DMRSport p₂. In case of the DMRS port p₂ to which precoding different fromthat of the PCRS port q₁ is applied, the channel value for the DMRS portp₂ with respect to the l-th OFDM symbol and the k-th RE may be estimatedas shown in Equation 9.

ĥ _(k,l) ^(p) ² ={tilde over (h)} _(k,2) ^(p) ² exp(j∠(Δ{circumflex over(θ)}_(k,l)))   Equation 9

Hereinafter, various embodiments of the present disclosure will bedescribed regarding a method for applying the same precoding to both oneDMRS port and one DMRS port.

The associated relation for phase noise estimation between one DMRS portgroup and one PCRS port may be presumed. The one DMRS port group ispresumed as being formed of DMRS ports p₁, p₂, P_(N), and the one PCRSport is presumed as q₁. In this case, N=1 or N>1. In addition, theassociated relation for phase noise estimation between M DMRS portgroups and M PCRS ports may be presumed. In this case, the m-th DMRSport group has the associated relation with the PCRS port q_(m) forphase noise estimation. In this case, one DMRS port group may be formedof one DMRS port (N=1) or formed of two or more DMRS ports (N>1).

The above-described various embodiments may be used to define theassociated relation for the phase noise estimation. This is, however,exemplary only and not to be construed as a limitation. Alternatively,any other method may be used to define the associated relation for thephase noise estimation. The following description may be applied basedon the associated relation for phase noise estimation between given oneDMRS port group and one PCRS port, and may be irrelevant to a detailedmethod regarding how to define the associated relation for the phasenoise estimation.

One DMRS port included in the one DMRS port group may apply the sameprecoding as that of the one PCRS port.

With respect to the PCRS port q_(i) and the DMRS port p_(j) which havethe associated relation with each other, the base station may use thesame MIMO transmission scheme but may not apply the same arbitraryprecoding.

Also, with respect to the PCRS port q_(i) and the DMRS port p_(j) whichhave the associated relation with each other, the base station may usethe same MIMO transmission scheme and apply the same arbitraryprecoding.

If the number of DMRS ports is equal to the number of associated PCRSports (namely, in case of N=1), the base station may apply the sameprecoding to each of the DMRS port p_(i) and the associated PCRS portq_(i). Namely, the terminal may presume that the same precoding isapplied to each of the DMRS port p_(i) and the associated PCRS portq_(i). The base station may explicitly deliver allocation informationfor the DMRS port and allocation information for the PCRS port to theterminal through the DCI. Alternatively, the base station may explicitlydeliver allocation information for only the DMRS port to the terminalthrough the DCI, and may instruct the terminal on the number of PCRSport allocations being N through the DCI. In this case, the terminal mayimplicitly know that the PCRS port q_(i) which is the same as the DMRSport number is allocated (i.e., p_(i)=q_(i) for i=1, . . . , N).

If one PCRS port q₁ and a plurality of DMRS ports p₁, p₂, . . . , p_(N)have the associated relation with each other, the base station may applythe same precoding to one PCRS port q₁ and one DMRS port p₁ of theplurality of DMRS ports p₁, p₂, . . . , p_(N). Namely, the terminal maypresume that the same precoding is applied to the DMRS port p₁ and theassociated PCRS port q₁. The base station may explicitly deliverallocation information for the DMRS port and allocation information forthe PCRS port to the terminal through the DCI. Alternatively, the basestation may explicitly deliver allocation information for only the DMRSport to the terminal through the DCI, and may instruct the terminal onthe number of PCRS port allocations being 1 through the DCI. In thiscase, the terminal may implicitly know that the PCRS port q₁ which isthe same as the DMRS port number p₁ is allocated (i.e., p₁=q₁).

If the PCRS port q_(m) and the m-th DMRS port group have the associatedrelation with each other, the base station may apply the same precodingto the PCRS port q_(m) and one DMRS port p_(1,m) having the lowest indexfrom among N DMRS ports p_(1,m), p_(2,m), . . . , p_(N,m) included inthe m-th DMRS port group. Namely, the terminal may presume that the sameprecoding is applied to the DMRS port p_(1,m) and the PCRS port q_(m).The base station may explicitly deliver allocation information for theDMRS port group and allocation information for the PCRS port to theterminal through the DCI. Alternatively, the base station may explicitlydeliver allocation information for only the DMRS port group to theterminal through the DCI, and may instruct the terminal on the number ofPCRS port allocations per DMRS port group being 1 through the DCI. Inthis case, the terminal may implicitly know that the PCRS port q_(m)which is the same as the DMRS port number p_(1,m) is allocated (i.e.,p_(1,m)=q_(m)).

According to the above-described embodiments, the terminal may presumethat the same precoding is applied to one DMRS port having the lowestindex included in the one DMRS port group and one PCRS port having theassociated relation with the DMRS port group. Based on the assumption ofsame precoding, the terminal may perform channel estimation.

In addition, based on embodiments to be described below, the terminalmay be further instructed by the base station on whether the sameprecoding is presumed between the one DMRS port and the one PCRS port.

Through one of the following methods, the base station may inform theterminal whether the same arbitrary precoding is applied to the PCRSport q_(i) and the DMRS port p₁ having the associated relation with eachother.

Using one bit contained in the DCI, the base station may indicate thatthe same precoding is applied to the associated DMRS and PCRS portsallocated by the corresponding DCI. Namely, if the DCI indicates “1”(i.e., if 1 is included), the terminal may presume that the sameprecoding is applied to one PCRS port and one DMRS port included in oneDMRS port group according to the above-discussed embodiments. If the DCIindicates “0”, the terminal may not presume that the same precoding asthe one PCRS port is applied to any DMRS port included in the one DMRSport group. Alternatively, such an indication may be applied in reverse.

Using a bitmap of length M contained in the DCI, the base station mayindicate whether the same precoding is applied to the associated DMRSand PCRS ports allocated by the corresponding DCI. In this case, thenumber of PCRS ports allocated by the DCI is M, and one PCRS port mayhave the associated relation with one or more DMRS ports. Using a bitmapof length M for each of the PCRS ports, the base station may instructthe terminal on whether the same precoding is applied to each PCRS portand the associated DMRS port.

If it is instructed that the same precoding is applied to one PCRS portand the associated DMRS port, the terminal may presume that the sameprecoding is applied to the PCRS port and the first DMRS port among theDMRS ports associated with the PCRS port. This corresponds to the casewhere the associated relation for phase estimation is set to M DMRS portgroups and M PCRS ports.

If the m-th bit in the bitmap of length M included in the DCI has avalue “1”, the terminal presume that the same precoding is applied tothe PCRS port q_(m) and the DMRS port p_(1,m) having the lowest indexamong the DMRS ports included in the m-th DMRS port group. If the m-thbit has a value “0”, the terminal may not presume that the sameprecoding is applied to the PCRS port q_(m) and the DMRS port p_(1,m)having the lowest index among the DMRS ports included in the m-th DMRSport group.

Based on DMRS port allocation information included in the DCI, the basestation may instruct that the same precoding is applied to some DMRSport combinations and the associated PCRS port. The DMRS port allocationinformation may be as shown in Tables 5 and 6 below.

For example, if the DCI includes “0” as the DMRS port allocationinformation in accordance with Table 5, the terminal may not presumethat the same precoding is applied to the DMRS port 8 and the associatedPCRS port. If “1” is included, the terminal may presume that the sameprecoding is applied to the DMRS port 8 and the associated PCRS port. If“5” is included in Table 5, the terminal may not presume that the sameprecoding is applied to one or more PCRS port(s) having the associatedrelation with respect to the DMRS port 8 and the DMRS port 9.

If “6” is indicated in Table 5 and if one PCRS port q₁ having theassociated relation with the DMRS ports 8 and 9 is allocated, theterminal may presume the same precoding for both the DMRS port 8 and thePCRS port q₁.

If “6” is indicated in Table 5 and if PCRS ports q_(i) and q₂respectively having the associated relations with the DMRS ports 8 and 9are allocated, the terminal may presume the same precoding for both theDMRS port 8 and the PCRS port q₁ and may also presume the same precodingfor both the DMRS port 9 and the PCRS port q₂.

In addition, using the DCI, the base station may inform the terminalwhether single-user MIMO (SU-MIMO) transmission or multi-user MIMO(MU-MIMO) transmission. In this case, the terminal may presume that thesame precoding is applied to the DMRS port and the associated PCRS portwith respect to the SU-MIMO transmission only.

For the above methods, the base station may perform instructions to theterminal by using, instead of the DCI, various kinds of controlinformation including RRC signaling, MAC CE, or system information block(SIB).

TABLE 5 Value Message 0 1 Layer, port 8 (Ch. estimation w/o OCC) 1 1Layer, port 8 (Ch. estimation w/o OCC; the same precoding both for theDMRS port and its associated PCRS port) 2 1 Layer, port 9 (Ch.estimation w/o OCC) 3 1 Layer, port 10 (Ch. estimation w/o OCC) 4 1Layer, port 11 (Ch. estimation w/o OCC) 5 2 Layers, ports {8, 9} (Ch.estimation w/o OCC) 6 2 Layers, ports {8, 9} (Ch. estimation w/o OCC;the same precoding both for the DMRS port(s) and its associated PCRSport(s)) 7 2 Layers, ports {10, 11} (Ch. estimation w/o OCC) 8 2 Layers,ports {8, 12} (OCC = 2) 9 2 Layers, ports {9, 13} (OCC = 2) 10 2 Layers,ports {10, 14} (OCC = 2) 11 2 Layers, ports {11, 15} (OCC = 2) 12-15Reserved

TABLE 6 Value Message 0 1 Layer, port 8 (Ch. estimation w/o OCC) 1 1Layer, port 8 (Ch. estimation w/o OCC; the same precoding both for theDMRS port and its associated PCRS port) 2 1 Layer, port 9 (Ch.estimation w/o OCC) 3 1 Layer, port 10 (Ch. estimation w/o OCC) 4 1Layer, port 11 (Ch. estimation w/o OCC) 5 2 Layers, ports {8, 9} (Ch.estimation w/o OCC) 6 2 Layers, ports {8, 9} (Ch. estimation w/o OCC;the same precoding both for the DMRS port(s) and its associated PCRSport(s)) 7 2 Layers, ports {10, 11} (Ch. estimation w/o OCC) 8 2 Layers,ports {8, 12} (OCC = 2) 9 2 Layers, ports {9, 13} (OCC = 2) 10 2 Layers,ports {10, 14} (OCC = 2) 11 2 Layers, ports {11, 15} (OCC = 2) 12 2Layers, ports {8, 12} (OCC = 2; the same precoding both for the DMRSport(s) and its associated PCRS port(s)) 13 2 Layers, ports {9, 13} (OCC= 2; the same precoding both for the DMRS port(s) and its associatedPCRS port(s)) 14 2 Layers, ports {10, 14} (OCC = 2; the same precodingboth for the DMRS port(s) and its associated PCRS port(s)) 15 2 Layers,ports {11, 15} (OCC = 2; the same precoding both for the DMRS port(s)and its associated PCRS port(s))

Hereinafter, various embodiments of the present disclosure will bedescribed. This embodiment proposes a setting method for one DMRSantenna port group (or a port group) and a method for allocating onePCRS port having the same precoding as one DMRS port in the port group.

The base station may set M DMRS port groups through RRC signaling or MACCE. Herein, M=1 or M>1. One DMRS port group may include N DMRS ports,where N=1 or N>1. Table 7 shows one method of DMRS port grouping in caseof M=2 and N=4. Table 8 shows the DMRS port grouping method in case ofM=1 and N=8.

TABLE 7 DMRS port group DMRS port(s) Group #1 8, 9, 10, 11 Group #2 12,13, 14, 15

TABLE 8 DMRS port group DMRS port(s) Group #1 8, 9, 10, 11, 12, 13, 14,15 Group #2 Null

The base station may allocate DMRS ports p₁, . . . , p_(L) to theterminal by using one DCI. Through the RRC signaling or the MAC CEsetting, the terminal may know which DMRS port group includes each ofthe DMRS ports p₁, . . . , p_(L). If a modulation and coding scheme(MCS) level of a physical downlink shared channel (PDSCH) allocatedthrough the DCI is greater than a specific threshold value, the terminalmay know PCRS allocation information according to the following methodseven through the DCI has no allocation information for the PCRS port.The threshold value of the MCS level of the PDSCH may be set in advancein the terminal by the base station through the RRC signaling or the MACCE. In the following description, it is presumed that the MCS level ofthe PDSCH allocated by the DCI is greater than a specific thresholdvalue.

When all of the DMRS ports p₁, . . . , p_(L) allocated through the DCIbelong to one DMRS port group, the terminal may presume that one PCRSport q₁ is allocated. In this case, the one PCRS port q₁ may have thesame value as the DMRS port p₁.

For example, it is presumed that the base station sets the DMRS portgroup as shown in Table 8 above. Thereafter, if the base stationallocates the DMRS ports (p₁, p₂)=(8, 9) to the terminal through oneDCI, the terminal may know that the DMRS ports are all included in thesame DMRS port group. Also, even though there is no specific PCRSallocation information in the DCI, the terminal may presume that onePCRS port q₁=8 having the same number as the first port p₁=8 of theallocated DMRS ports is allocated. Then the terminal may perform PCRSreception for the PCRS port q₁=8 at the time and frequency resourcelocation corresponding to the RE mapping of the PCRS port q₁=8. Theterminal may perform the operations proposed based on the presumptionthat the same precoding is applied to both the DMRS port p₁=8 and thePCRS port q₁=8.

In another example, it is presumed that the base station sets the DMRSport group as shown in Table 8 above. Thereafter, if the base stationallocates the DMRS ports (p₁, p₂)=(10, 11) to the terminal through oneDCI, the terminal may know that the DMRS ports are all included in thesame DMRS port group. Also, even though there is no specific PCRSallocation information in the DCI, the terminal may presume that onePCRS port q_(i)=10 having the same number as the first port p₁=10 of theallocated DMRS ports is allocated. Then the terminal may perform PCRSreception for the PCRS port q₁=10 at the time and frequency resourcelocation corresponding to the RE mapping of the PCRS port q₁=10. Theterminal may perform the operations proposed in an embodiment on theassumption that the same precoding is applied to both the DMRS portp₁=10 and the PCRS port q₁=10.

When the DMRS ports p₁, . . . , p_(L) allocated through the DCI aredivided into and belong to M′ DMRS port groups, the terminal may presumethat M′ PCRS ports q₁, q₂, . . . , q_(M′) are allocated. If DMRS portsincluded in the m-th DMRS port group among the DMRS ports allocatedthrough the DCI are {p_(1,m), p_(2,m), . . . }, the m-th PCRS port q_(m)among the M′ PCRS ports may have the same value as the DMRS portp_(1,m).

For example, it is presumed that the base station sets the DMRS portgroup as shown in Table 7 above. Thereafter, if the base stationallocates the DMRS ports (p₁, p₂, p₃, p₄)=(8, 9, 12, 13) to the terminalthrough one DCI, the terminal may know that the DMRS ports are includedin different M′ (=2) DMRS port groups. In this case, the terminal knowsthat the first DMRS port group has p₁, p₂ and the second DMRS port grouphas p₃, p₄.

Even though there is no specific PCRS allocation information in the DCI,the terminal may presume that the PCRS port q₁=8 having the same numberas the first DMRS port p₁=8 included in the first DMRS group isallocated, and may also presume that the PCRS port q₂=12 having the samenumber as the first DMRS port p₃=12 included in the second DMRS group isallocated. Then the terminal may perform PCRS reception for therespective PCRS ports at the time and frequency resource locationscorresponding to the RE mapping of the PCRS ports q₁=8, q₂=12. Theterminal may perform the operations proposed in an embodiment on theassumption that the same precoding is applied to both the DMRS port p₁=8and the PCRS port q₁=8. Also, the terminal may perform the operationsproposed in an embodiment on the assumption that the same precoding isapplied to both the DMRS port p₃=12 and the PCRS port q₂=12.

For example, it is presumed that the base station sets the DMRS portgroup as shown in Table 7 above. Thereafter, if the base stationallocates the DMRS ports (p₁, p₂, p₃, p₄)=(10, 11, 14, 15) to theterminal through one DCI, the terminal may know that the DMRS ports areincluded in different M′ (=2) DMRS port groups. In this case, theterminal knows that the first DMRS port group has p₁, p₂ and the secondDMRS port group has p₃, p₄.

Even though there is no specific PCRS allocation information in the DCI,the terminal may presume that the PCRS port q₁=10 having the same numberas the first DMRS port p₁=10 included in the first DMRS group isallocated, and may also presume that the PCRS port q₂=14 having the samenumber as the first DMRS port p₃=14 included in the second DMRS group isallocated. Then the terminal may perform PCRS reception for therespective PCRS ports at the time and frequency resource locationscorresponding to the RE mapping of the PCRS ports q₁=10, q₂=14. Theterminal may perform the operations based on the presumption that thesame precoding is applied to both the DMRS port p₁=10 and the PCRS portq₁=10. Also, the terminal may perform the operations proposed in anembodiment on the presumption that the same precoding is applied to boththe DMRS port p₃=14 and the PCRS port q₂=14.

FIGS. 4A and 4B are diagrams illustrating operations of a base stationand a terminal when the base station performs a signal transmission tothe terminal by using a single antenna port according to variousembodiments of the present disclosure.

Referring to FIG. 4A, operations of the base station are illustratedaccording to various embodiments of the present disclosure. At operation400, the base station transmits, to the terminal, DCI including thefollowing information. The DCI is for transmission using a singleantenna port and includes one antenna port (p₁ in case of DMRS, q₁ incase of PCRS) of each of DMRS and PCRS allocated to the terminal, andinformation indicating whether the same precoding is applied to bothreference signals, DMRS and PCRS. In this case, the same precoding isapplied to antenna ports of both indicated reference signals.

According to another embodiment of the present disclosure, theinformation indicating whether the same precoding is applied to bothreference signals may not be included in the DCI and may be set inadvance through RRC signaling or MAC CE. Alternatively, the terminal mayalways presume that the same precoding is applied to both referencesignals with respect to at least one or more antenna ports in accordancewith embodiments of the present disclosure.

The allocation information for the PCRS port may not be explicitlyincluded in the DCI. In this case, according to embodiments of thepresent disclosure, the terminal may implicitly obtain allocationinformation for the PCRS port.

Thereafter, the base station transmits downlink data to the terminal. Atthis time, the base station performs scrambling 410 and modulationmapping 420 for a codeword, performs RE mapping 430 of a modulatedsymbol of one layer associated with an antenna port, perform OFDM signalgeneration 440 and transmits the OFDM signal. At this time, the basestation transmits DMRS and PCRS together with the data, and bothreference signals are transmitted with antenna port numbers indicated bythe DCI. The antenna port numbers of both reference signals may be thesame.

Referring to FIG. 4B, operations of the terminal are illustratedaccording to various embodiments of the present disclosure. At operation450, the terminal receives a signal (data) from the base station andextracts, at operation 455, information on a transmission method, DMRSand PCRS antenna ports, and information indicating whether the sameprecoding is applied, based on the DCI received previously. Then, theterminal estimates channel information based on the DMRS at operation460, and also estimates phase noise (PN) information based on the PCRSat operation 465. At this time, the terminal processes the PCRS byassuming that the same precoding is applied to both DMRS and PCRS. Then,the terminal performs phase noise compensation based on the channelinformation and the phase noise information at operation 470, andperforms a symbol detection and channel decoding based on channelinformation with the compensated phase noise at operation 475. Theoperations 465 and 470 may be performed based on the methods discussedabove in an embodiment.

FIGS. 5A and 5B are diagrams illustrating operations of a base stationand a terminal when the base station performs a signal transmission tothe terminal by using a transmit diversity according to variousembodiments of the present disclosure.

Referring to FIG. 5A, operations of the base station are illustrated. Atoperation 500, the base station transmits, to the terminal, DCIincluding the following information. The DCI is for transmission using atransmit diversity and includes two antenna ports (p₁, p₂ in case ofDMRS, q₁, q₂ in case of PCRS) of each of DMRS and PCRS allocated to theterminal, and information indicating whether the same precoding isapplied to both reference signals, DMRS and PCRS. In this case, the sameprecoding is applied to both DMRS and PCRS having the same antenna portnumber. Namely, the same precoding is applied to both p₁ and q₁, and thesame precoding is applied to both p₂ and q₂.

According to another embodiment of the present disclosure, theinformation indicating whether the same precoding is applied to bothreference signals may not be included in the DCI and may be set inadvance through RRC signaling or MAC CE. Alternatively, the terminal mayalways presume that the same precoding is applied to both referencesignals with respect to at least one or more antenna ports in accordancewith embodiments of the present disclosure.

The allocation information for the PCRS port may not be explicitlyincluded in the DCI. In this case, according to embodiments of thepresent disclosure, the terminal may implicitly obtain allocationinformation for the PCRS port.

Thereafter, the base station transmits downlink data to the terminal. Atthis time, the base station performs scrambling 505 and modulationmapping 510 for one codeword, performs layer mapping 515 of a modulatedsymbol to two layers, and applies precoding 520 based on the transmitdiversity to the symbol mapped to the layers. Then, the base stationperforms RE mapping 525 of the precoded symbol associated with each oftwo antenna ports, generates the OFDM signal 530, and transmits the OFDMsignal. At this time, the base station transmits DMRS and PCRS togetherwith the data, and both reference signals are transmitted using antennaport numbers indicated by the DCI. The antenna port numbers of bothreference signals having the same precoding may be the same (namely,p₁=q₁, p₂=q₂).

Referring to FIG. 5B, operations of the terminal are illustrated. Atoperation 550, the terminal receives a signal (data) from the basestation and extracts, at operation 555, information on a transmissionmethod, DMRS and PCRS antenna ports, and information indicating whetherthe same precoding is applied, based on the DCI. Then, the terminalestimates channel information based on the DMRS port p₁ at operation560, and also estimates PN information based on the PCRS port q₁ atoperation 565. At this time, the terminal processes the PCRS bypresuming that the same precoding is applied to both DMRS and PCRS. Inaddition, the terminal estimates channel information based on the DMRSport p₂ at operation 570, and also estimates phase noise informationbased on the PCRS port q₂ at operation 575. At this time, the terminalprocesses the PCRS by presuming that the same precoding is applied toboth DMRS and PCRS. Then, the terminal performs phase noise compensationbased on the channel information estimated based on the DMRS port p₁ andthe phase noise information estimated based on the PCRS port q₁ atoperation 580, performs phase noise compensation based on the channelinformation estimated based on the DMRS port p₂ and the phase noiseinformation estimated based on the PCRS port q₂ at operation 585, andperforms a symbol detection and channel decoding based on channelinformation with the compensated phase noise at operation 590. Theoperations 565, 580, 575 and 585 may be performed based on the methodsdiscussed above in an embodiment.

FIGS. 6A and 6B are diagrams illustrating operations of a base stationand a terminal when the base station performs a signal transmission tothe terminal by using a transmit diversity according to variousembodiments of the present disclosure.

Referring to FIG. 6A, operations of the base station are illustrated. Atoperation 600, the base station transmits, to the terminal, DCIincluding the following information. The DCI is for transmission using atransmit diversity and includes two DMRS antenna ports p₁, p₂ and onePCRS antenna port q₁ allocated to the terminal, and informationindicating whether the same precoding is applied to both referencesignals, DMRS and PCRS. In this case, according to embodiments of thepresent disclosure, the same precoding is applied to both the DMRS portp₁ and the PCRS port q₁.

According to another embodiment of the present disclosure, theinformation indicating whether the same precoding is applied to bothreference signals may not be included in the DCI and may be set inadvance through RRC signaling or MAC CE. Alternatively, the terminal mayalways presume that the same precoding is applied to both referencesignals with respect to at least one or more antenna ports in accordancewith embodiments of the present disclosure.

The allocation information for the PCRS port may not be explicitlyincluded in the DCI. In this case, according to embodiments of thepresent disclosure, the terminal may implicitly obtain allocationinformation for the PCRS port.

Thereafter, the base station transmits downlink data to the terminal. Atthis time, the base station performs scrambling 605 and modulationmapping 610 for one codeword, performs layer mapping 615 of a modulatedsymbol to two layers, and applies precoding 620 based on the transmitdiversity to the symbol mapped to the layers. Then, the base stationperforms RE mapping 625 of the precoded symbol associated with eachantenna port, generates an OFDM signal 630, and transmits the OFDMsignal. At this time, the base station transmits DMRS and PCRS togetherwith the data, and both reference signals are transmitted using antennaport numbers indicated by the DCI. At this time, one layer istransmitted together with the DMRS port p₁ and the PCRS port q₁, and theother layer is transmitted together with the DMRS port p₂. The antennaport numbers of both reference signals having the same precoding may bethe same (namely, p₁=q₁).

Referring to FIG. 6B, operations of the terminal are illustrated. Atoperation 650, the terminal receives a signal (data) from the basestation and extracts, at operation 655, information on a transmissionmethod, DMRS and PCRS antenna ports, and information indicating whetherthe same precoding is applied, based on the DCI received previously.Then, the terminal estimates channel information based on the DMRS portp₁ at operation 660, and also estimates PN information based on the PCRSport q₁ at operation 665. At this time, the terminal processes the PCRSby assuming that the same precoding is applied to both DMRS and PCRS. Inaddition, the terminal estimates channel information based on the DMRSport p₂ at operation 670. Then, the terminal performs phase noisecompensation based on the channel information estimated based on theDMRS port p₁ and the phase noise information estimated based on the PCRSport q₁ at operation 675, performs phase noise compensation based on thechannel information estimated based on the DMRS port p₂ and the phasenoise information estimated based on the PCRS port q₁ at operation 680,and performs a symbol detection and channel decoding based on channelinformation with the compensated phase noise at operation 685. Theoperations 665, 675 and 680 may be performed based on the methodsdiscussed above in an embodiment.

FIGS. 7A and 7B are diagrams illustrating operations of a base stationand a terminal when the base station performs a signal transmission tothe terminal by using a spatial multiplexing with a single layeraccording to various embodiments of the present disclosure.

FIG. 7A shows the operations of the base station. Referring to FIG. 7A,at operation 700, the base station transmits, to the terminal, DCIincluding the following information. The DCI is for transmission using aspatial multiplexing (SM) and includes one DMRS antenna port p₁ and onePCRS antenna port q₁ allocated to the terminal, and informationindicating whether the same precoding is applied to both referencesignals, DMRS and PCRS. In this case, the same precoding is applied toboth the DMRS antenna port p₁ and the PCRS antenna port q₁.

According to another embodiment of the present disclosure, theinformation indicating whether the same precoding is applied to bothreference signals may not be included in the DCI and may be set inadvance through RRC signaling or MAC CE. Alternatively, the terminal mayalways presume that the same precoding is applied to both referencesignals with respect to at least one or more antenna ports in accordancewith embodiments of the present disclosure.

The allocation information for the PCRS port may not be explicitlyincluded in the DCI. In this case, according to embodiments of thepresent disclosure, the terminal may implicitly obtain allocationinformation for the PCRS port.

Thereafter, the base station transmits downlink data to the terminal. Atthis time, the base station performs scrambling 705 and modulationmapping 710 for one codeword, performs resource element mapping 715 of amodulated symbol of one layer, generates an OFDM signal 720 from thesymbol, and applies the same precoding 725 to both DMRS and PCRS (e.g.,W is applied to both the DMRS and PCRS), and transmits using a pluralityof physical antennas. At this time, the base station transmits DMRS andPCRS together with the data, using the DMRS antenna port p₁ and the PCRSantenna port q₁. The antenna port numbers of both reference signalshaving the same precoding may be the same (namely, p₁=q₁).

Referring to FIG. 7B, operations of the terminal are illustrated. Atoperation 750, the terminal receives a signal (data) from the basestation and extracts, at operation 755, information on a transmissionmethod, DMRS and PCRS antenna ports, and information indicating whetherthe same precoding is applied, based on the DCI. Then, the terminalestimates channel information based on the DMRS port p₁ at operation760, and also estimates PN information based on the PCRS port q₁ atoperation 765. At this time, the terminal processes the PCRS by assumingthat the same precoding is applied to both DMRS and PCRS. Then, theterminal performs phase noise compensation based on the channelinformation estimated based on the DMRS port p₁ and the phase noiseinformation estimated based on the PCRS port q₁ at operation 770, andperforms a symbol detection and channel decoding based on channelinformation with the compensated phase noise at operation 775. Theoperations 765 and 770 may be performed based on the methods discussedabove in an embodiment.

FIGS. 8A and 8B are diagrams illustrating operations of a base stationand a terminal when the base station performs a signal transmission tothe terminal by using a spatial multiplexing with a single layeraccording to various embodiments of the present disclosure.

Referring to FIG. 8A, operations of the base station are illustrated andare different from FIGS. 7A and 7B in that different precoders areapplied to DMRS and PCRS. At operation 800, the base station transmits,to the terminal, DCI including the following information. The DCI is fortransmission using a spatial multiplexing and includes one DMRS antennaport p₁ and one PCRS antenna port q_(i) allocated to the terminal, andinformation indicating whether the same precoding is applied to bothreference signals, DMRS and PCRS. In this case, the same precoding isnot applied to both DMRS and PCRS.

Thereafter, the base station transmits downlink data to the terminal. Atthis time, the base station performs scrambling 805 and modulationmapping 810 for one codeword, performs RE mapping 815 of a modulatedsymbol of one layer, generates an OFDM signal 820 from the symbol, andapplies different precodings 825 to both DMRS and PCRS (e.g., W isapplied to DMRS ports and Z is applied to PCRS ports) using a pluralityof physical antennas, and transmits data. At this time, the base stationtransmits DMRS and PCRS together with the data, using the DMRS antennaport p₁ and the PCRS antenna port q₁.

Referring to FIG. 8B, operations of the terminal are illustrated. Atoperation 850 the terminal receives a signal (i.e., data) from the basestation and extracts, at operation 855, information on a transmissionmethod, DMRS and PCRS antenna ports, and information indicating whetherthe same precoding is applied, based on the DCI. Then, the terminalestimates channel information based on the DMRS port p₁ at operation860, and also estimates PN information based on the PCRS port q_(i) atoperation 865. At this time, the terminal processes the PCRS bypresuming that the same precoding is not applied to both DMRS and PCRS.Then, the terminal performs phase noise compensation based on thechannel information estimated based on the DMRS port p₁ and the phasenoise information estimated based on the PCRS port q₁ at operation 870,and performs a symbol detection and channel decoding based on channelinformation with the compensated phase noise at operation 875. Theoperations 865 and 870 may be performed based on the methods discussedabove in an embodiment.

FIGS. 9A and 9B are diagrams illustrating operations of a base stationand a terminal when the base station performs a signal transmission tothe terminal by using a spatial multiplexing with two layers accordingto various embodiments of the present disclosure.

Referring to FIG. 9A, operations of the base station are illustrated. Atoperation 900, the base station transmits, to the terminal, DCIincluding the following information. The DCI is for transmission usingSM and includes two antenna ports (p₁, p₂ in case of DMRS, q₁, q₂ incase of PCRS) of each of DMRS and PCRS allocated to the terminal, andinformation indicating whether the same precoding is applied to bothreference signals, DMRS and PCRS. In this case, the same precoding isapplied to both DMRS and PCRS having the same antenna port number.Namely, the same precoding is applied to both p₁ and q₁, and the sameprecoding is applied to both p₂ and q₂.

According to another embodiment of the present disclosure, theinformation indicating whether the same precoding is applied to bothreference signals may not be included in the DCI and may be set inadvance through RRC signaling or MAC CE. Alternatively, the terminal mayalways presume that the same precoding is applied to both referencesignals with respect to at least one or more antenna ports in accordancewith embodiments of the present disclosure.

The allocation information for the PCRS port may not be explicitlyincluded in the DCI. In this case, according to embodiments of thepresent disclosure, the terminal may implicitly obtain allocationinformation for the PCRS port.

Thereafter, the base station transmits downlink data to the terminal. Atthis time, the base station performs scrambling 905 and modulationmapping 910 for each of two codewords, performs layer mapping 915 of amodulated symbol to each of two layers, performs RE mapping 920 of thelayer-mapped symbol associated with each of two antenna ports, generatesan OFDM signal 925 from the symbol, applies the same precoding 930 tothe associated DMRS and PCRS (e.g., W is applied to both the DMRS andPCRS), and transmits using a plurality of physical antennas. At thistime, the base station transmits DMRS and PCRS together with the data,and both reference signals are transmitted using two antenna portsindicated by the DCI. The antenna port numbers of both reference signalshaving the same precoding may be the same (namely, p₁=q₁, p₂=q₂).

Referring to FIG. 9B, operations of the terminal are illustrated. Atoperation 950, the terminal receives a signal (data) from the basestation and extracts, at operation 955, information on a transmissionmethod, DMRS and PCRS antenna ports, and information indicating whetherthe same precoding is applied, based on the DCI received previously.Then, the terminal estimates channel information based on the DMRS portp₁ at operation 960, and also estimates PN information based on the PCRSport q₁ at operation 965. At this time, the terminal processes the PCRSby assuming that the same precoding is applied to both DMRS and PCRS. Inaddition, the terminal estimates channel information based on the DMRSport p₂ at operation 970, and also estimates phase noise informationbased on the PCRS port q₂ at operation 975. At this time, the terminalprocesses the PCRS by presuming that the same precoding is applied toboth DMRS and PCRS. Then, the terminal performs phase noise compensationbased on the channel information estimated based on the DMRS port p₁ andthe phase noise information estimated based on the PCRS port q₁ atoperation 980, performs phase noise compensation based on the channelinformation estimated based on the DMRS port p₂ and the phase noiseinformation estimated based on the PCRS port q₂ at operation 985, andperforms a symbol detection and channel decoding based on channelinformation with the compensated phase noise at operation 990. Theoperations 965, 975, 980 and 985 may be performed based on the methodsdiscussed above in an embodiment.

FIGS. 10A and 10B are diagrams illustrating operations of a base stationand a terminal when the base station performs a signal transmission byusing a spatial multiplexing with two layers according to variousembedment of the present disclosure.

Referring to FIG. 10A, operations of the base station are illustratedand differ from the example in FIGS. 9A and 9B in that two DMRS portsand one PCRS port are allocated. At operation 1000, the base stationtransmits, to the terminal, DCI including the following information. TheDCI is for transmission using a spatial multiplexing and includes DMRSand PCRS antenna ports (p₁, p₂ in case of DMRS, q₁ in case of PCRS)allocated to the terminal, and information indicating whether the sameprecoding is applied to both reference signals, DMRS and PCRS. In thiscase, the same precoding is applied to both DMRS and PCRS having thesame antenna port number. Namely, the same precoding is applied to bothp₁ and q₁.

According to another embodiment of the present disclosure, theinformation indicating whether the same precoding is applied to bothreference signals may not be included in the DCI and may be set inadvance through RRC signaling or MAC CE. Alternatively, the terminal mayalways presume that the same precoding is applied to both referencesignals with respect to at least one or more antenna ports in accordancewith embodiments of the present disclosure.

The allocation information for the PCRS port may not be explicitlyincluded in the DCI. In this case, according to embodiments of thepresent disclosure, the terminal may implicitly obtain allocationinformation for the PCRS port.

Thereafter, the base station transmits downlink data to the terminal. Atthis time, the base station performs scrambling 1005 and modulation 1010for each of two codewords, performs layer mapping 1015 of a modulatedsymbol to each of two layers, performs RE mapping 1020 of thelayer-mapped symbol associated with each antenna port, generates an OFDMsignal 1025 from the symbol, applies the same precoding 1030 to theassociated DMRS and PCRS (e.g., W is applied to both DMRS and PCRSports), and transmits using a plurality of physical antennas. At thistime, the base station transmits DMRS and PCRS together with the data.At this time, one layer is transmitted together with the DMRS port p₁and the PCRS port q₁, and the other layer is transmitted together withthe DMRS port p₂. The antenna port numbers of both reference signalshaving the same precoding may be the same (namely, p₁=q₁).

Referring to FIG. 10B, operations of the terminal are illustrated. Atoperation 1050, the terminal receives a signal (data) from the basestation and extracts, at operation 1055, information on a transmissionmethod, DMRS and PCRS antenna ports, and information indicating whetherthe same precoding is applied, based on the DCI. Then, the terminalestimates channel information based on the DMRS port p₁ at operation1060, and also estimates PN information based on the PCRS port q₁ atoperation 1065. At this time, the terminal processes the PCRS byassuming that the same precoding is applied to both DMRS and PCRS. Inaddition, the terminal estimates channel information based on the DMRSport p₂ at operation 1070. Then, the terminal performs phase noisecompensation based on the channel information estimated based on theDMRS port p₁ and the phase noise information estimated based on the PCRSport q₁ at operation 1075, performs phase noise compensation based onthe channel information estimated based on the DMRS port p₂ and thephase noise information estimated based on the PCRS port q₁ at operation1080, and performs a symbol detection and channel decoding based onchannel information with the compensated phase noise at operation 1085.The operations 1065, 1075 and 1080 may be performed based on the methodsdiscussed above in an embodiment.

FIGS. 11A and 11B are diagrams illustrating operations of a base stationand a terminal when the base station performs a signal transmission tothe terminal by using a spatial multiplexing with two layers accordingto various embodiments of the present disclosure.

Referring to FIG. 11A, operations of the base station are illustratedusing different precoders that are applied to DMRS and PCRS. Atoperation 1100, the base station transmits, to the terminal, DCIincluding the following information. The DCI is for transmission using aspatial multiplexing and includes two antenna ports (p₁, p₂ in case ofDMRS, q₁, q₂ in case of PCRS) of each of DMRS and PCRS allocated to theterminal, and information indicating whether the same precoding isapplied to both reference signals, DMRS and PCRS. In this case, the sameprecoding is not applied to both DMRS and PCRS.

Thereafter, the base station transmits downlink data to the terminal. Atthis time, the base station performs scrambling 1105 and modulationmapping 1110 for each of two codewords, performs layer mapping 1115 of amodulated symbol to each of two layers, performs RE mapping 1120 of thelayer-mapped symbol associated with each of two antenna ports, andgenerates an OFDM signal 1125 from the symbol. In this case, the basestation transmits data by applying different precodings 1130 to DMRS andPCRS and using a plurality of physical antennas (e.g., W is applied toDMRS and Z is applied to PCRS). At this time, the base station transmitsDMRS and PCRS together with the data, and both reference signals aretransmitted using two antenna ports indicated by the DCI.

Referring to FIG. 11B, operations of the terminal are illustrated. Atoperation 1150, the terminal receives a signal (data) from the basestation and extracts, at operation 1155, information on a transmissionmethod, DMRS and PCRS antenna ports, and information indicating whetherthe same precoding is applied, based on the DCI. Then, the terminalestimates channel information based on the DMRS port p₁ at operation1160, and also estimates PN information based on the PCRS port q₁ atoperation 1165. At this time, the terminal processes the PCRS by notassuming that the same precoding is applied to both DMRS and PCRS. Inaddition, the terminal estimates channel information based on the DMRSport p₂ at operation 1170, and also estimates phase noise informationbased on the PCRS port q₂ at operation 1175. At this time, the terminalprocesses the PCRS by not assuming that the same precoding is applied toboth DMRS and PCRS. Then, the terminal performs phase noise compensationbased on the channel information estimated based on the DMRS port p₁ andthe phase noise information estimated based on the PCRS port q₁ atoperation 1180, performs phase noise compensation based on the channelinformation estimated based on the DMRS port p₂ and the phase noiseinformation estimated based on the PCRS port q₂ at operation 1185, andperforms a symbol detection and channel decoding based on channelinformation with the compensated phase noise at operation 1190.

FIGS. 12A and 12B are diagrams illustrating operations of a base stationand a terminal when the base station performs a signal transmission tothe terminal by using a spatial multiplexing with two layers accordingto various embodiments of the present disclosure.

Referring to FIG. 12A, operations of the base station are illustratedhaving two DMRS ports and one PCRS port allocated and differentprecoders are used for DMRS and PCRS. At operation 1200, the basestation transmits, to the terminal, DCI including the followinginformation. The DCI is for transmission using a spatial multiplexingand includes DMRS and PCRS antenna ports (p₁, p₂ in case of DMRS, q₁ incase of PCRS) allocated to the terminal, and information indicatingwhether the same precoding is applied to both reference signals, DMRSand PCRS. In this case, the same precoding is not applied to DMRS andPCRS.

Thereafter, the base station transmits downlink data to the terminal. Atthis time, the base station performs scrambling 1205 and modulationmapping 1210 for each of two codewords, performs mapping layer 1215 of amodulated symbol to each of two layers, performs RE mapping 1220 of thelayer-mapped symbol associated with each antenna port, generates an OFDMsignal 1225 from the symbol, and applies different precodings 1230 toDMRS and PCRS (e.g., W for DMRS and Z for PCRS), and transmits using aplurality of physical antennas. At this time, the base station transmitsDMRS and PCRS together with the data. At this time, one layer istransmitted together with the DMRS port p₁, and the other layer istransmitted together with the DMRS port p₂.

Referring to FIG. 12B, operations of the terminal are illustrated. Atoperation 1250, the terminal receives a signal (data) from the basestation and extracts, at operation 1255, information on a transmissionmethod, DMRS and PCRS antenna ports, and information indicating whetherthe same precoding is applied, based on the DCI. Then, the terminalestimates channel information based on the DMRS port p₁ at operation1260, and also estimates PN information based on the PCRS port q₁ atoperation 1265. At this time, the terminal processes the PCRS by notassuming that the same precoding is applied to both DMRS and PCRS. Inaddition, the terminal estimates channel information based on the DMRSport p₂ at operation 1270. Then, the terminal performs phase noisecompensation based on the channel information estimated based on theDMRS port p₁ and the phase noise information estimated based on the PCRSport q₁ at operation 1275, performs phase noise compensation based onthe channel information estimated based on the DMRS port p₂ and thephase noise information estimated based on the PCRS port q₁ at operation1280, and performs a symbol detection and channel decoding based onchannel information with the compensated phase noise at operation 1285.The operations 1265, 1275 and 1280 may be performed based on the methodsdiscussed above in an embodiment.

Now, a structure and operation of a channel estimation block (orreferred to as a channel estimator) of a terminal will be described.

FIG. 13 is a diagram illustrating a structure and operation of a channelestimation block of a terminal when the same precoder is used for a DMRSand a PCRS according to an embedment of the present disclosure.

Referring to FIG. 13, the channel estimation block 1300 includes a PNinformation estimation block 1310, a channel information estimationblock 1320, and a PN compensation block 1330. The PN informationestimation block 1310 estimates PN based on PCRS, and is formed of a PNestimator 1312 to be used in case of assuming the same precoder and a PNestimator 1314 to be used in case of not assuming the same precoder. Incase of FIG. 13 in which the same precoder is used, a received PCRS isinputted to the PN estimator 1312. PN information estimated by the PNestimator 1312 is inputted to the PN compensation block 1330 togetherwith channel information estimated by the channel information estimationblock 1320 based on a received DMRS. Then the PN compensation block 1330calculates and outputs channel information with compensated PN. The PNinformation estimated by the PN estimator 1312 may be as shown inEquation 3. The channel information with compensated PN may be as shownin Equation 2.

FIGS. 14Aand 14B are diagrams illustrating a structure and operation ofa channel estimation block of a terminal when the same precoder is notused for a DMRS and a PCRS according to various embodiments of thepresent disclosure.

Referring to FIG. 14A, the channel estimation block 1400 includes a PNinformation estimation block 1410, a channel information estimationblock 1420, and a PN compensation block 1430. The PN informationestimation block 1410 estimates PN based on PCRS, and is formed of a PNestimator 1412 to be used in case of assuming the same precoder and a PNestimator 1414 to be used in case of not assuming the same precoder. Incase of FIG. 14A in which the same precoder is not used, a received PCRSis inputted to the PN estimator 1414. PN information estimated by the PNestimator 1414 is inputted to the PN compensation block 1430 togetherwith channel information estimated by the channel information estimationblock 1420 based on a received DMRS. Then the PN compensation block 1430calculates and outputs channel information with compensated PN. The PNinformation estimated by the PN estimator 1414 may be as shown inEquation 4. The channel information with compensated PN may be as shownin Equation 5.

Referring to FIG. 14B, a structure and operation of a channel estimationblock of a terminal are illustrated when two DMRS ports p₁, p₂ and onePCRS port q₁ are allocated and the same precoder is used for the DMRSport p₁ and the PCRS port q₁. The channel estimation block 1450 includesa PN estimator 1460, channel information estimation blocks 1470 and1475, and PN compensation blocks 1480 and 1485. PN information estimatedby the PN estimator 1460 is inputted to the PN compensation blocks 1480and 1485 together with channel information estimated by the channelinformation estimation blocks 1470 and 1475 based on a received DMRS.Then each of the PN compensation blocks 1480 and 1485 calculates andoutputs channel information with compensated PN. The PN informationestimated by the PN estimator 1460 may be as shown in Equation 8. Thechannel information corresponding to the DMRS ports p₁ with compensatedPN may be as shown in Equation 7, and the channel informationcorresponding to the DMRS ports p₂ with compensated PN may be as shownin Equation 9.

FIG. 15 is a diagram illustrating a structure of a terminal according toan embodiment of the present disclosure.

Referring to FIG. 15, the terminal may include a transceiver 1500, acontroller 1510, and a storage 1530. In the present disclosure, thecontroller 1510 may be defined as a circuit, an application-specificintegrated circuit, or at least one processor.

The transceiver 1500 may transmit and receive signals to and from thebase station. For example, the transceiver 1500 may receive systeminformation from the base station and may receive a synchronizationsignal or a reference signal. In particular, the transceiver 1500 mayreceive DCI, DMRS, and PCRS according to embodiments of the presentdisclosure.

The controller 1510 may control the overall operation of the terminalaccording to embodiments of the present disclosure. For example, thecontroller 1510 may control a signal flow between blocks to perform theabove-discussed operations as shown in flow diagrams. Also, thecontroller 1510 includes a channel estimator 1520, which may be thechannel estimation block as shown in FIGS. 13, 14A and 14B. The channelestimator 1520 may generate channel information from which a phase noiseis compensated based on DMRS and PCRS. A method for generating thechannel information is as described above in various embodiment of thepresent disclosure. This method or related process may be performed bythe controller 1510.

The storage 1530 may store at least one of informationtransmitted/received through the transceiver 1500 and informationgenerated through the controller 1510. For example, the storage 1530 maystore the estimated channel information.

FIG. 16 is a diagram illustrating a structure of a base stationaccording to an embodiment of the present disclosure.

Referring to FIG. 16, the base station may include a transceiver 1600, acontroller 1610, and a storage 1630. In the present disclosure, thecontroller 1610 may be defined as a circuit, an application-specificintegrated circuit, or at least one processor.

The transceiver 1600 may transmit and receive signals to and from theterminal and any other network entity. For example, the transceiver 1600may transmit system information to the terminal and may transmit asynchronization signal or a reference signal. In particular, thetransceiver 1600 may transmit DCI, DMRS, and PCRS according toembodiments of the present disclosure.

The controller 1610 may control the overall operation of the basestation according to embodiments of the present disclosure. For example,the controller 1610 may control a signal flow between blocks to performthe above-discussed operations as shown in flow diagrams. Also, thecontroller 1610 includes a reference signal generator 1620, which maygenerate PCRS and DMRS depending on whether the same precoding isapplied, and then send the PCRS and DMRS to the terminal through thetransceiver 1600. This process may be performed by the controller 1610.

The storage 1630 may store at least one of informationtransmitted/received through the transceiver 1600 and informationgenerated through the controller 1610.

While the present disclosure has been shown and described with referenceto various embodiments thereof, it will be understood by those skilledin the art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the present disclosure asdefined by the appended claims and their equivalents.

What is claimed is:
 1. A method of a base station in a communicationsystem, the method comprising: determining whether a first precoding isapplied to a demodulation reference signal (DMRS) and a phasecompensation reference signal (PCRS) to be transmitted to a terminal;generating the DMRS and the PCRS based on whether the first precoding isapplied to the DMRS and the PCRS; and transmitting data, the DMRS, andthe PCRS to the terminal.
 2. The method of claim 1, further comprising:transmitting, to the terminal, downlink control information includingantenna information indicating at least one antenna port associated withthe DMRS and the PCRS and precoding information indicating whether thefirst precoding is applied.
 3. The method of claim 2, wherein theprecoding information indicates that the first precoding is applied toat least one antenna port associated with the DMRS and at least oneantenna port associated with the PCRS.
 4. The method of claim 1, whereinthe DMRS is used to estimate channel information, and wherein the PCRSis used to estimate a phase noise to compensate the channel information.5. A method of a terminal in a communication system, the methodcomprising: receiving data, a demodulation reference signal (DMRS), anda phase compensation reference signal (PCRS) from a base station;determining whether a first precoding is applied to the DMRS and thePCRS; and estimating channel information using the DMRS and the PCRSbased on whether the first precoding is applied to the DMRS and thePCRS.
 6. The method of claim 5, further comprising: receiving, from thebase station, downlink control information including antenna informationindicating at least one antenna port associated with the DMRS and thePCRS and precoding information indicating whether the first precoding isapplied.
 7. The method of claim 6, wherein the precoding informationindicates that the first precoding is applied to at least one antennaport associated with the DMRS and at least one antenna port associatedwith the PCRS.
 8. The method of claim 5, further comprising: estimatingchannel information based on the DMRS; estimating a phase noise based onthe PCRS; and compensating the channel information based on the phasenoise.
 9. A base station in a communication system, the base stationcomprising: a transceiver configured to transmit and receive a signal;and a controller configured to: determine whether a first precoding isapplied to a demodulation reference signal (DMRS) and a phasecompensation reference signal (PCRS) to be transmitted to a terminal,generate the DMRS and the PCRS based on whether the first precoding isapplied to the DMRS and the PCRS, and transmit data, the DMRS, and thePCRS to the terminal.
 10. The base station of claim 9, wherein thecontroller is further configured to transmit, to the terminal, downlinkcontrol information including antenna information indicating at leastone antenna port associated with the DMRS and the PCRS and precodinginformation indicating whether the first precoding is applied.
 11. Thebase station of claim 10, wherein the precoding information indicatesthat the first precoding is applied to at least one antenna portassociated with the DMRS and at least one antenna port associated withthe PCRS.
 12. The base station of claim 9, wherein the controller isfurther configured to: estimate channel information based on the DMRS,estimate a phase noise based on the PCRS, and compensate the channelinformation based on the phase noise.
 13. A terminal in a communicationsystem, the terminal comprising: a transceiver configured to transmitand receive a signal; and a controller configured to: receive data, ademodulation reference signal (DMRS), and a phase compensation referencesignal (PCRS) from a base station, determine whether a first precodingis applied to the DMRS and the PCRS, and estimate channel information byusing the DMRS and the PCRS based on whether is the first precoding isapplied to the DMRS and the PCRS.
 14. The terminal of claim 13, whereinthe controller is further configured to receive, from the base station,downlink control information including antenna information indicating atleast one antenna port associated with the DMRS and the PCRS andprecoding information indicating whether the first precoding is applied.15. The terminal of claim 14, wherein the precoding informationindicates that the first precoding is applied to at least one antennaport associated with the DMRS and at least one antenna port associatedwith the PCRS.
 16. The terminal of claim 13, wherein the controller isfurther configured to: estimate channel information based on the DMRS,estimate a phase noise based on the PCRS, and compensate the channelinformation based on the phase noise.
 17. The terminal of claim 13,wherein the controller is further configured to determine whether thefirst precoding is applied to the DMRS and a second precoding is appliedto the PCRS.